From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45088) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1addul-0000Tm-VF for qemu-devel@nongnu.org; Wed, 09 Mar 2016 08:12:36 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1addui-0006lM-2N for qemu-devel@nongnu.org; Wed, 09 Mar 2016 08:12:35 -0500 Received: from e06smtp13.uk.ibm.com ([195.75.94.109]:43156) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1adduh-0006l1-PG for qemu-devel@nongnu.org; Wed, 09 Mar 2016 08:12:31 -0500 Received: from localhost by e06smtp13.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 9 Mar 2016 13:12:29 -0000 Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by d06dlp01.portsmouth.uk.ibm.com (Postfix) with ESMTP id 5FDBF17D8062 for ; Wed, 9 Mar 2016 13:12:54 +0000 (GMT) Received: from d06av11.portsmouth.uk.ibm.com (d06av11.portsmouth.uk.ibm.com [9.149.37.252]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id u29DCQcI66977840 for ; Wed, 9 Mar 2016 13:12:26 GMT Received: from d06av11.portsmouth.uk.ibm.com (localhost [127.0.0.1]) by d06av11.portsmouth.uk.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id u29DCP4O017821 for ; Wed, 9 Mar 2016 06:12:25 -0700 Date: Wed, 9 Mar 2016 14:12:22 +0100 From: Cornelia Huck Message-ID: <20160309141222.3031ea4d.cornelia.huck@de.ibm.com> In-Reply-To: <56E01F90.9020702@de.ibm.com> References: <1455470231-5223-1-git-send-email-pbonzini@redhat.com> <1455470231-5223-6-git-send-email-pbonzini@redhat.com> <56E01544.6060305@de.ibm.com> <56E01D3F.1060204@redhat.com> <56E01F00.7050905@de.ibm.com> <56E01F90.9020702@de.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 5/8] virtio-blk: fix "disabled data plane" mode List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Christian Borntraeger Cc: Paolo Bonzini , qemu-devel@nongnu.org On Wed, 9 Mar 2016 14:05:20 +0100 Christian Borntraeger wrote: > On 03/09/2016 02:02 PM, Christian Borntraeger wrote: > > On 03/09/2016 01:55 PM, Paolo Bonzini wrote: > >> > >> > >> On 09/03/2016 13:21, Christian Borntraeger wrote: > >>> I have some random crashes at startup > >>> > >>> Stack trace of thread 48326: > >>> #0 0x000002aa2e0cce46 bdrv_co_do_rw (qemu-system-s390x) > >>> #1 0x000002aa2e159e8e coroutine_trampoline (qemu-system-s390x) > >>> #2 0x000003ffbc35150a __makecontext_ret (libc.so.6) > >>> > >>> > >>> that I was able to bisect. > >>> commit 2906cddfecff21af20eedab43288b485a679f9ac does crash regularly, > >>> 2906cddfecff21af20eedab43288b485a679f9ac^ does not. > >>> > >>> I will try to find somebody that looks into that - unless you have an idea. > >> > >> The only random idea is to move > >> > >> vblk->dataplane_started = true > >> > >> to the beginning of virtio_blk_data_plane_start rather than the end. > >> > >> Paolo > >> > > > > Indeed > > > > diff --git a/hw/block/dataplane/virtio-blk.c b/hw/block/dataplane/virtio-blk.c > > index 36f3d2b..1908d59 100644 > > --- a/hw/block/dataplane/virtio-blk.c > > +++ b/hw/block/dataplane/virtio-blk.c > > @@ -195,6 +195,7 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) > > if (vblk->dataplane_started || s->starting) { > > return; > > } > > + vblk->dataplane_started = true; > > > > s->starting = true; > > s->vq = virtio_get_queue(s->vdev, 0); > > @@ -235,7 +236,6 @@ void virtio_blk_data_plane_start(VirtIOBlockDataPlane *s) > > fail_guest_notifiers: > > s->disabled = true; > > s->starting = false; > > - vblk->dataplane_started = true; > > } > > > > /* Context: QEMU global mutex held */ > > > > seems to fix the issue. > > Hmmm, no another crash, just seems to happen less often. What about the proposal in <56C34414.90809@redhat.com>, i.e. move setting the started flag out of dataplane entirely?